Tamp retraction device for tamp type packer



Oct. 25, 1960 w s, BQHLMAN 2,957,382

TAMP RETRACTIN DEVICE FOR TAM? TYPE PACKER Filed May 13, 1957 2 Sheets-Sheet 2 WALTER S. BOHLMAN LN VEN TUR BY g ,@PM

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cules Powder ECompany, Wilmington, Del., a corporation of Delaware Filed May 13, 1957, ser. No. 658,736 s claims. tcl.' srs- 20) This invention relates to an improved 4tamp type packer. In one taspect, this invention relates to 'a piston-cylinder assembly particularly advantageously applied in combination with a tamp type packer and associated with fluid pressure sources for moving tarnps from the work in response 4to lling of the containers, and for moving the tamp from the work when the cycle is stalled by failure ofthe container to fill. In still another aspect, this invention relates to a piston type assembly in combination with Va tamp vibratory type packer and associated with a plurality of fluid pressure sources for separating a tamp rod from the Work, independently of structure in the said assembly for normally moving the tamp during the regular packing cycle. In still another aspect, this invention relates to a method for operating a tamp vibratory type packer wherein a separate uid pressure source is utilized in the retraction of a tamp to resume the packing cycle stalled by failure of the tamp to separate from the work.

In the copending application of Walter S. Bohlman land lack D. Hayes, I r., Serial No. 346,206, tiled April l, 1953, now abandoned, is disclosed and claimed a packer Wherein pulverulent materials are driven from a hopper by action of reciprocating tamp rods through nipples in the hopper iloor and allowed to gravitate into containers, the latter being meanwhile maintained in a state of vibration to consolidate the material to a uniformly packed density.

The packer above referred to contains la platen adapted to support, and vibrate and impart vibration to, one or more of the containers to receive solids driven from the hopper. Each tamp rod is connected with a piston in a cylinder-piston assembly contained in a reciprocating crosshead driven by 4a suitable power source, the associated fluid pressure sources of the assembly maintaining the piston under fluid pressure to hold the tamp rod in an extended or packing position, i.e., in operating position. When the container fills, pulverulent material builds up in the nipple and causes the rod to retract ya distance equal to the length of the core formed in the nipp-le. By the rods retraction, the piston is forced b-ack within the cylinder an equal distance and final-ly permits access behind the piston of a fluid pressure higher than the above said fluid pressure to overcome the same and further force back the piston a suiiicient distance to separate the tamp rod from the work material. The crosshead is adapted to continuous reciprocation and when the last container is filled and the last rod raised, means is -actuated for terminating vibration `of the platen, lowering the platen, and moving the filled containers to a separate stage for crimping or further handling as the case may be. Empty containers lare then brought to the platen and the cycle is repeated. The entire operation is automatic.

As applied to the packaging of explosives, for economic and other reasons, the container is fabricated from a paper-type material. In some instances the paper container, `as `a result of the vibration or defects in structure, splits, bulges, 'breaks or in some other manner fails so that the pulverulent material being fed to it fails to enter or escapes and the container cannot fill. As the machine,

in order to maintain the operating cycle, must awaitthe retraction of the last tamp rod which in turn must -await the filling of the last container and the building of a core, the failure of any container not only stalls the operating cycle but also subjects the other containers that are filled to a.prolonged state of vibration and, consequently, to a too high density of the packed material.

This invention is concerned with an improved pistoncylinder assembly with means for moving such a laggard tamp rod from a tamp system of the above described type, independently of structure of the said assembly for moving the tamp from the work during the regular packing cycle, in a manner such that the packing operation cycle stalled by the laggard tamp can be resumed Without adversely affecting the density of the material in the normally packed containers.

An object of this invention is to provide a tamp-type packer in combination with a device for separating a tamp from the work independently of structure for so separating the tamp during the regular packing cycle. Another object is to provide a piston-cylinder assembly for resuming the normal cycle of a tamp-type vibratory packer above described, which has been stalled by failure of a last tamp rod to retract and actuate the means for continuation of the cycle. Another object is to provide a method for Voperating a tamp-type packer of the above described type, wherein a laggard tamp which would cause stalling of the packing cycle is caused to retract, to thus continue the cycle, independently of the manner in which the tamp would be retracted during the normal cycle. Another object is to provide a piston-cylinder assembly particularly applicable for retracting one or more of the tamps in a tamp-vibratory packer, independently of structure for that purpose dur-ing the regular packing cycle. Other objects and aspects will be apparent in light of the accompanying disclosure and the appended claims.

yIn accordance with this invention, a piston-cylinder type assembly is provided which is particularly advantageously applied in combination with a tamp vibratory type packer to cause resumption of the normal cycle when stalled during the packing portion of the cycle by failure of a tamp rod to move from the work during the normal cycle, which comprises a huid-tight cylinder; a piston disposed fluid-tight Within said cylinder; a rod in said cylinder connected with an end of the said piston and extending longitudinally from the said piston end and through an end of said cylinder; a first conduit opening into said cylinder at a point in a side thereof so as to be in direct communication with `a side of said piston when said piston is moved toward the above said cylinder end to extend said rod from said cylinder, and said piston closing said first conduit when in said direct communication therewith; a second conduit opening into said cylinder at a point in a side thereof intermediate said piston and said cylinder end when said piston closes said first conduit; conduit means in said cylinder connecting said second conduit with said piston end only when said piston closes said first conduit; and a third conduit opening into said cylinder at la point intermediate said `rst conduit and the end of said cylinder opposite the above described cylinder end.

Further, in accordance with this invention, an improvement is provided in the operation of a tamp-vibratory type packer of the kind above described, wherein tamp rods are each afiixed to a piston in a cylinder contained in a reciprocating crosshead yand are reciprocated therewith to contact a solid pulverulent material to move said material into a packed position in a container, wherein each said piston is maintained by fluid pressure in said cylinder to support said piston and rod in its working position during the said reciprocation to elect the tamping and each said piston is moved by force ofhigher iluid pressure so as to move the said piston and rod away from the working position in response to filling of the container, wherein only after the last tamp rod is moved from said working position, said machine automatically transfers the'ciilled containers, and wherein at least one of said containers fails to till and the operating cycle of the machine is thereby stalled, the said improvement providing for `resumption of said operating cycle when said container fails to fill, which comprises maintaining a source ofiiuid at said high pressure available for application to the said piston to move same so as to move said rod from said operating position only for a distance suicient to allow the first said high-pressure air supply to be applied to the said piston, and applying air pressure to said piston from said source when said container fails to till, thereby engaging the said piston with the original high-pressure fluid source to reestablish the operating cycle of the machine.

The invention is illustrated with reference to the drawings, of which Figure l is an enlarged detail of the pistoncylinder assembly of this invention; Figure 2 is an elevational section taken along line 2-2 of Figure 3; Figure 3 is a cross section taken along line 3-3 of Figure 2, including crimping structure not shown in Figure 2; and Figurse 4 is a schematic showing illustrative of one form of apparatus by which uid under pressure can be conveyed to the piston-cylinder assembly of this invention.

With reference to Figure 1, fluid-tight cylinder 48 is closed at its ends 48C and 48d by cylinder heads 48a and 48]). Piston 49 is disposed in cylinder 48 in Huid-tight relation with the cylinder walls and slidable therein by seals 49a and 49b, preferably of the O-ring type. Conduit or port 53 in a side Wall of cylinder 48 is connected with conduit 54 and header 55. Rod 44 in cylinder 48 is con- 48a as a tamp rod for a tamp-type packer described hereinafter. Rod 44 is sealed in cylinder head 48a by spaced apart O-ring type seals 74 and 75, or in any other suitable manner. Conduit 54 opens by port 53 in the side of cylinder 48 at a point so as to be in direct communication with a side of piston 49, and to be closed by sealed piston 49, when the said piston is moved toward closure 48a to extend rod 44 to the tarnping or working position. In the embodiments shown, port 53 is disposed intermediate the O-ring seals 49a and 49h, for maintaining piston 49 fluid tight in cylinder 48, and is substantially adjacent the O-ring seal 49a. /Conduit 71, connected with header 72, opens via port 70, generally through a side wall of cylinder 48, into cylinder head 48a and annulus 76 disposed around rod 44 therein. Port 70,

moved, the maximum distance from cylinder 48 through cylinder end 48e, the minimum distance in any event being the distance between seals 49a and 49b. Piston 49 in any case does to permit seal 49a to move to a prevent movement of seal 49a past port 53.

The groove mlts 1ts direct communication with port 70 so long as piston 49 is disposed to close port 53 but such that it terminates its communication with positioned so as to close port 53. Rod seal 75 in cylinder head 48a is disposed intermediate port 70 and the exterior end of head y48a at a point so as always to encompass groove 73.

Conduit 5.1 connected to manifold 52 opens into a side of cylinder 48 via port 50 which is spaced from port 53 preferably so as to be in close proximity to cylinder head 48b but, in any event, always in direct communication with the interior of cylinder 48. Piston 49 is always so disposed in cylinder 48 with its end 49d in direct communication with port 50. Preferably, closure head 48h acts as a stop for piston 49 to prevent passage of the piston to a point such that its end 49d would be out of direct communication with port 50.

Rod `44a in cylinder 48 is connected with piston 49 at end 49d and extends longitudinally from piston end 49d through cylinder head 48b in sealed relation therewith by O-ring type seal 75a.

An orced cam member 56, outside cylinder 48, is slidably mounted on an extension 48e of cylinder head 4811 and is freely movable longitudinally. It is adapted to be pushed slightly upward and away from cylinder 48 by the end of rod 44a engaging extension 58 when rod 44a is extended from cylinder 48 by movement of piston 49 toward closure head 4817. `Cam member 56 is adapted to be moved slightly downward toward cylinder 48 by nut 57 on the end of rod 44a when the piston 49 is extended toward closure 48a and substantially in contact therewith.

Near the lower extremity of cam member 56 there is an extended portion 59 which, as cam member 56 is moved toward cylinder 48, engages arm member 60 attached to a rotatable shaft 61 mounted in bearing member 62. Shaft 61 is spring loaded, as illustrated by spring 61a, to rotate clockwise. Such clockwise rotation is limited by engagement of members 60 and 59. Shaft 61 has an attached end lever 63 which, by rotation, engages and actuates valve means 64 for further actuation of the tamp-vibratory machine as described hereinafter.

A device of Figure 1, as illustrated with reference to Figures 2 and 3, is contained with a plurality of similar devices on the crosshead member 47 so that a plurality of tamp rods are operated simultaneously as crosshead assembly 42. As each cam member 56 rises under the inuence of piston 49 and rod 44a, its extension 59 clears elongated member 60, thereby releasing some of the force that holds shaft 61 in a stationary position to which it has been rotated counterclockwise against the tension of spring 61a. However, until all piston-cylinder assemblies have operate-d to remove extensions 59 from contact with elongated members 60, shaft 6.1 remains stationary. When the extension 59 of the last unit operates to clear and release member 60, the pull of tension of spring 61a rotates shaft 61 clockwise, causing actuation of valve means 64 with resulting termination of vibration of the platen and lowering of lthe same to continue the cyclic operation.

With reference to Figures 2 and 3, the tamp-vibratory type packer embodying the piston-cylinder assem bly of this invention as applied to packing explosives is shown supported by a frame 10. Platen 11 is supported adjacent each end of resilient mountings 12 and can be raised or lowered by means of iluid pressure within cylinders 13. A pneumatic vibrator 15 is attached to the underside of the platen 11 at 14 with the power stroke of the piston 15a being in the vertical direction or normal to the plane of the platen 11. A rack 16 for receiving filled cartridges is rotatably mounted on an axle 17 and is actuated to three positions by pneumatic cylinders not shown. A crimping assembly 19 is shown disposed directly above the rack 16 when rack 16 is in the vertical position shown. The crimping assembly is divided into two sections, 21 and 22. The lower section 22 contains folding dies 23, while the crimping plungers 24 are mounted in the upper section 21 and extend downwardly into dies 23. Piston rods (not shown) lead froma piston in a pneumatic cylinder (not shown) through the member 21 and are pressed against member 22. The entire crimp assembly 19 is synchronized with the unloading of containers from the platen into the rack so as to be pulled down upon a container in upright rack 16 to make the crimp.

A shuttle 30 is pivotally mounted at each end on arms 31 which are in turn pivotally mounted on a subframe 31a adjustable up and down for different lengths of cartridges. Pneumatic cylinders are advantageously employed to actuate the movement of the shuttle during operation. Cylinder 33 mounted on the arms 31 and connected to clevis 32 Vat the base of the shuttle 30, by actuation causes the bottom of the shuttle to swing forward and upward to the position shown by the dotted lines 35. Cylinders 34 mounted on the subframe 31u andconnected to the clevises 32a on the arms 31, by actuation, cause'the arms 31 and the attached shuttle 30 to swing down and back to the position shown by the dotted lines 36. l

Containers 37 held in the vertically positioned vshuttle 30 are shown with their closed bottoms resting on platen 11. Directly above the shuttle V30 is mounted hopper 38, the bottom of which is formed by a nipple plate 39. The nipples 40 ente-r into the mouths of the shells-containers 37 when the shuttle and the platen have each been raised to filling position, the shuttle having been raised prior to rise of the platen.4 Tandem stirrers 41l are mounted in the hopper 38 on each side of the nipples 40. Crosshead assembly 42 is disposed above the hopper 38 and is reciprocated in its entirety by cranks 43 connecting rods 43ava11d rods 43b connected through shaft 43c tothe power source. Contained in the crosshead assembly 42 are a plurality of piston-cylinder assemblies of Figure 1 described hereinabove. Each rod 44 serves as a tamp rod operating in hopper 38 and is advantageously connected with a wood rod 45, in the packaging of explosives, so that the interior of hopper 38 is free from the presence of metals, except for the nipple plate The machine of Figures 1 through 3 operates asV fol- The explosive material to be packed is introduced uniformly to the hopper 38 by suitable conveyor means 38a. The shuttle 30, while in the dotted position 36, is initially loaded with empty shells by means not shown. The shells are loosely held in the shuttle and are free to move longitudinally therein. Through retraction of the rod of pneumatic cylinder 33 and the extension of the rods of pneumatic cylinders 34, the shuttle 30 is raised to a vertical position so that the shells 37 rest upon the platen 11. Then, through the extension of the rods of cylinders 13, the platen 11 is raised sufficiently to push the shells 37 up within the connes of the shuttle 30 until their open ends embrace the nipples 40 in plate 39 that forms the bottom of hopper 38. Meanwhile, the stirrers 41 are continuously rotating and the crosshead assembly 42 is reciprocating vertically withrthe tamps 44 attached to elements 45-46 directly above the nipples 40. The tamps being in their shortened position, the tamp tip 46 very nearly touches the powder in the hopper when at the end of its downward stroke. As soon as the raised shells 37 embrace the nipples '40, the vibrator 15 -is automatically started and the tamps are extended so that the stroke of the tamp tip 46 extends from above the powder down through the nipples 40, but no further. The sticks 45, with tips 46 continuously reciprocating with the crosshead, force the explosive through the nipples 40 and into the containers where it is continuously consolidated by the vibration imparted to the shells 37 by the vibrating platen 11. Due to uniform introduction of the composition into the hopper 38, the synchronous distribution by stirrers 41, and the reciprocating action of the rods 44 and 45, the shells are illed practically simultaneously, thus exposing the explosive in each shell to practically the same amount of vibration. When the level of consolidated powder rises above the egress orifice of the nipples 4G, `the powder is then consolidated in the nipples 40 by tamping action of the sticks 45. All this time, low pressure air is being introduced into the upper part of the cylinders 48 through the port 50. The pressure of this air is such that with each succeeding increment of powder that is packed in the nipples 40, lthe effective stroke of the rod 44 is shortened by compression of air in the upper part of the cylinder 48 by the piston 49. On the up-stroke of the crosshead assembly, however, the low pressure air again fully lengthens the stroke of the stick 45 and the next increment of powder packed in the nipple by the'succeeding stroke is packed to a density suicient to still further shorten the effective stroke of the stick 45. When each nipple is filled to the desired level, the piston 49 is raised by action of the powder packed in the -nipple to a point where seal 49h passes port 53 and allows high pressure air to flow from header 55 into the lower part of cylinder 48. High pressure air from port 53 then overcomes the low pressure air and the pistonV 49 is then forced into the upper portion of the cylinder 48 to withdraw the stick 45 from contact with the powder in the nipple or hopper. As the high pressure air forces each rod 44 to its Yupper limit of travel, each cam 56 is lifted and successively clears the lever 60. When the last -rod 44 rises and the lastV cam 56 clears the lever 60, the spring loaded rod 61 is allowedto rotate clockwise to actuate a valving mechanism 64 which shuts off the ow of air to the vibrator 15 and reverses the air in cylinders 13 to lower the platen 11. Lowering of the platen 11 allows the shells 37 to fall away from the nipples 40, whereupon the consolidated, continuous column of powder in the shell breaks away from the nipples which remain sealed by the cores packed therein.

Cylinder 33 is now actuated to swing the bottom of the shuttle 30 and shells 37 outwardly to clear the platen as Shown by the dotted lines at 35. The loaded shells, loosely held by the shuttle 30, fall through the shuttle 3G into the'rack 16. Cylinders 34 are then automatically actuated to swing down the now empty shuttle 30 to thehorizontal position shown by the dotted lines 36. A new group of empty shells is then inserted automatically into the shuttle 30 by an automatic shell feeding device (not shown). The cylinders 33 and 34 are then actuated to raise the shuttle 30 back into the vertical position .under the nipples 40. The platen 11 is then raised to engage the new shells with the nipples 40. At this point, the high pressure air in the cylinder 48 from port 53 is drained off to release the pressure below the piston 49. The low pressure air then forces each piston 49 down to extend the rods 44 to their full length below the crosshead. As the rods 44 are forced to their longest effective length, the nuts 57 force the cam 56 downward and the lever 60 is again The rod 61 is rotated counterclockwise, the valving mechanism 64 is reversed and is cocked or loaded for the next cycle. f

The crosshead assembly 42 has continuously reciprocated during this time and with the first stroke of the extended rods 44 and sticks 45, the cores which were built up in the nipples 40 are pushed into the empty shells and the loading and packing operation is repeated. In order to break the core, the initial stroke is under higher air pressure than d i 'ng the normal tamping operation. Assooiated structure for effecting the initially high pressure stroke is not shown. During the loading of this group of shells, the rack 16 which contains the loaded first group of shells is swung to the vertical position shown in Figure 3, and the crimping mechanism 19 is pulled downward, by pneumatic valve-cylinder assemblies not shown. As the folding dies 23 turn the edges of the mouths of the shells inwardly, the member 22 maintained apart from the member 21 by means not shown is stopped by means not shown, but 21 continues downwardly forcing the crimping plungers depressed.

24 down- Wardly through the folding dies 23 to complete the crimping operation.

forced outwardly by cylinder means (not Shown) to the dotted discharging position 58. The finished Ycartridges are discharged to a waiting tray or moving belt as may be desired.

and are assembled to the art. Hydraulic cylinders or equivalent cal elements which will eiect the necessary movement of the various parts of the apparatus may be substituted, if desired.

As the last tamp cam member 56 and its extension 59 clears elongated of the machine.

In the operation of the machine, the vibration imparted to the shell, particularly a shell of irregular construction,

port 70 and piston 49 is then subject to fluid pressure from port 53, the O-ring seals @9b having been raised to above port 53. `Once piston 49 is raised into operative mittng high pressure fluid into cylinder 48 via ports 53 and 70.

Referring to Figure 4, iluid under pressure, which ordinarily, is air, is withdrawn from low pressure source at a line Sl to header 55 of Figure l to maintain high pressure air available `for raising piston 49 as described hereinabove.

Valve assembly 84 contains any suitable normally open, threeway valve enough to permit and raise the piston 49 by Way of groove 73 so as to resume the packing cycle.

High pressure air, when desired, can be passed to header port 53 can be vented by way of header 72 and lines 91 and 95.

Air under pressure from lines 83, 86 and 88 provides timer-unit 90 with air for the actuation of -valve 92. The timer device of timer-unit 91B is set to cause opening vibration to effect undesirable Once air is passed through valve 92 from line 94 and the laggard tamp has thereby been raised, the normal cycle is resumed. When there are no laggard tamps, timer-unit 90 times out and Valve 92 opens after all tamps are up but such action has `no effect on the normal cycle, and the next time valve 84 is closed, timer-unit 99 is reset and valve 92 is closed. Any other suitable arrangement for delivery of uid under pressure to cylinder d8 can be employed as desired, the foregoing with reference to Figure 4 being by way of illustration only.

It is to be understood that the cylinder 48 can be closed by any suitable means, although cylinder heads 48a and 481; extending intocylinder 48y are'now preferred. One such alternative is a cap at each end 48C and 48d of cylinder 48 with any suitable means for communicating fiuid pressure from port 70 to the bottom 49e of piston 49. In one such embodiment, a closure member in cylinder 48 can be inserted intermediate port 70 and end 48e and containing a conduit in direct communication with port 70 and groove 73 when piston 49 is positioned so as to close port 53.

As will be evident to those skilled in the art, various modifications can be made or followed, in the light of the foregoing disclosure and discussion, without departing from the spirit or scope of the disclosure or from the scope of the claims.

What I claim and desire to protect by Letters Patent is:

1. Apparatus comprising a closed cylinder; a piston disposed fluid tight in said cylinder; a rod in said cylinder connected with an end of said piston and extending longitudinally from said piston end through a first end of said cylinder; a first conduit opening into said cylinder at a point in a side thereof so as to be in direct communica-tion with a side of said pistonwhen the said piston is moved toward said first cylinder end to extend said rod from said cylinder, and said piston closing said first conduit when in said direct communication therewith; a second conduit opening into said cylinder at a point in a side thereof intermediate said piston and said first cylinder end when said piston closes said first conduit; a groove extending along a side of said piston rod in direct closed communication with said piston end, and in direct closed communication with said second conduit so long as said piston closes said first conduit; and a third conduit opening into said cylinder at a point intermediate said first conduit and a second end of said cylinder.

2. In apparatus of claim 1, a first and a second cylinder head respectively in said first and second cylinder ends, as closure means for said cylinder; said third conduit opening into said cylinder at a point in close proximity to said second cylinder head and said second conduit opening into said cylinder at a point in direct contact with said first cylinder head; means for sealing said rod at separate points in said first cylinder head; an annulus formed in said first cylinder head around said rod intermediate said separate points; a passageway connecting said annulus withl said second conduit; and said groove being disposed to extend beyond said annulus toward the said first cylinder end for a distance so as to be in said direct closed communication with said second conduit so long as said piston closes said first conduit.

3. In a packing machine of the tamp type in combination with a reciprocable crosshead assembly, a fluid tight cylinder connected with said crosshead with its axis extending in the direction of reciprocation of said crosshead; a piston disposed fiuid tight in said cylinder; a rod in said cylinder connected with an end of said piston and extending longitudinally from said piston through a first end of said cylinder, as a tamp rod for said packer; a first conduit opening into said cylinder at a point in a side thereof so as to be in direct communication with a side of said piston When said piston is moved toward said first cylinder end to extend said rod from said cylinder, and said piston closing said first conduit when in said direct communication therewith; a second conduit opening into said cylinder at a point in a side thereof intermediate said piston and said first cylinder end when said piston closes said first conduit; conduit means l@ in said cylinder connecting said second conduit with said piston end only when said piston closes said first conduit; and a third conduit opening into said cylinder at a point intermediate said first conduit and a second t end of said cylinder.

4. In a packing machine of claim 3 said conduit means in said cylinder comprising a groove extending along a side of said piston rod in direct closed communication with the said end of said piston, and in direct closed communication with the said second conduit so long as said piston closes said first conduit.

5. In a packing machine of claim 3 a first and second cylinder head respectively in the said first and second ends of said cylinder, as closure means for said cylinder; said third conduit opening into said cylinder at a point in close proximity to said second cylinder head and said second conduit opening into said cylinder at a point in direct contact with said first cylinder head; means for sealing said rod at separate points in said rst cylinder head; said conduit means comprising an annulus formed in said first cylinder head around said rod intermediate the above said separate points, a passageway connecting said annulus with said second conduit, and a groove disposed in the side of said rod and extending longitudinally from said piston; and said groove being disposed to extend beyond said annulus toward the said first end of said cylinder for a distance so as to be in direct communication with said second conduit so long as said piston closes said first conduit.

6. In a packing machine of the tamp type in combination with a reciprocable crosshead assembly, a plurality of fluid-tight cylinders connected with said crosshead, said cylinders having their axes extending in the direction of reciprocation of said crosshead and adapted thereby to reciprocate with said crosshead; a piston disposed fluidtight in each said cylinder and a rod in each said cylinder connected with an end of said piston and extending longitudinally from said piston downwardly through a first end of said cylinder as a tamp rod for said packing machine; a hopper beneath said plurality of fluid-tight cylinders, and a plurality of nipples in the bottom of said hopper extending downwardly therethrough; each said nipple being in direct alignment with one of said tamp rods, and said hopper being spaced from said plurality of cylinders so that each said tamp rod, when at its down- Wardmost point of travel during reciprocation, extends into said hopper and through, but not substantially beyond, the bottom end of one of the said nipples to thereby tamp pulverulent materials from said hopper through said nipple; a first conduit opening into each of said cylinders at a point in a side thereof so as to be in direct communication with a side of the piston therein when it is moved toward said first cylinder end to extend said tamp rod from said cylinder, and said piston closing said first conduit when in said direct communication therewith; a first cylinder head in the said first end of said cylinder, and a second cylinder head in a second end of said cylinder, as closure means for said cylinder; a second conduit opening into each of said cylinders at a point in a side thereof in direct contact with said first cylinder head, and a third conduit opening into each of said cylinders at a point intermediate said first conduit and said second cylinder head and in close proximity to said second cylinder head; means for sealing said rod at separate points in said first cylinder head; an annulus formed in said first cylinder head around said rod intermediate the above said separate points; a passageway connecting said annulus with said second conduit; a groove disposed in the side of said rod and extending longitudinally from said piston, and said groove being disposed to extend beyond said annulus toward the said first end of said cylinder for a distance so as to be in direct communication with said second conduit so long as said piston closes said first conduit; a loW pressure fiuid conduit connected with each said third conduit for conveying fluid under pressure to said third conduit; a first high pressure fluid conduit connected with each said first conduit for conveying Huid to said first conduit under pressure greater than that in said low pressure conduit; a second high pressure conduit for conveying uid at a pressure about the same as that in said rst high pressure conduit, to said second conduit; a valve in said iirst high pressure conduit, maintained open, but adapted to be closed in response to expiration of a predetermined duration after rise of the last of said tamps from said working contact, and thereafter to be opened; and 'a valve in said second high pressure conduit, maintained closed, but adapted to be opened to permit communication of Huid pressure therein to said second conduit.

7. Apparatus of claim 6 wherein said valve in said sec- 15 2,515,323

ond high pressure conduit is a manually controlled valve.

References Cited in the file of this patent UNITED STATES PATENTS 351,657 Schofield Oct. 26, 1886 620,775 Hoffmann Mar. 7, 1899 1,346,064 Remmen July 6, 1920 2,502,547 Adams et al. Apr. 4, 1950 Stuart July 18, 1950 

